1. Field of the Invention
The present invention relates to a laser beam printer apparatus. More specifically, the present invention relates to a laser beam printer apparatus including a motor cover.
2. Description of the Background Art
A laser beam printer apparatus includes a plurality of rollers each of which is driven by a motor.
FIG. 11 exemplarily shows a schematic cross-sectional view of a laser beam printer apparatus. A front side of the laser beam printer apparatus is shown on a right side in FIG. 11. This laser printer is formed to eject a sheet for printing such as paper toward the front side.
Each part of the laser beam printer apparatus is arranged inside an exterior cover 45. A paper tray 31 housing paper or the like for printing is arranged in a lower portion of exterior cover 45. A pickup roller 32 for removing the paper or the like from paper tray 31 is arranged on a rear end portion of paper tray 31. The paper or the like is conveyed along a conveying path 75 in a direction indicated with an arrow 70. The paper or the like is ejected to an ejected paper tray 3.
A conveying roller 33 for conveying the paper or the like is arranged around conveying path 75. A photoconductive drum 35 and a transfer roller 34 for arranging toner in a desired shape on a surface of the paper or the like are also arranged around conveying path 75. In addition, a fixing roller 36 for fixing toner arranged on the surface to the paper or the like is arranged around conveying path 75.
A toner cartridge 30 filled with toner is arranged on a substantial center portion of exterior cover 45. Toner cartridge 30 is formed in a replaceable form and, when toner is insufficient, can be replaced with another toner cartridge 30 filled with toner. Toner cartridge 30 can be removed from the front side of the laser beam printer apparatus.
An agitation plate 39 for agitating filling toner is formed inside-toner cartridge 30. Agitation plate 39 is formed in a flat shape and one end portion thereof is supported with a support shaft 40. Agitation plate 39 is formed to rock around support shaft 40 to agitate internal toner.
A developer roll 38 for arranging toner on photoconductive drum 35 is formed in a portion inside toner cartridge 30 adjacent to photoconductive drum 35. Developer roll 38 is formed in a columnar shape having a length in a width direction corresponding to a length of photoconductive drum 35. Developer roll 38 is arranged to attain line contact with photoconductive drum 35.
A blade 37 is formed on a side surface of developer roll 38 with one end portion thereof extending toward the surface of developer roll 38. Blade 37 can remove excessive toner arranged on the surface of developer roll 38.
As described above, a plurality of rollers are arranged in the laser beam printer apparatus to perform conveying of a sheet for printing, transfer of toner and the like. These rollers are driven by a motor. The laser beam printer apparatus includes a frame body arranged inside exterior cover 45. Various rollers, the motor and the like are secured to the frame body. A horizontal plate 28 of the frame body formed to extend in a horizontal direction is shown in FIG. 11.
FIG. 12 is an enlarged perspective view of a portion of the frame body on which a motor is arranged. A frame body 29 arranged inside the exterior cover includes a side plate 26 formed to extend in a vertical direction and horizontal plate 28 formed to extend in the horizontal direction.
Each of side plate 26 and horizontal plate 28 is formed with a resin. A cartridge frame body 14 is formed on the inside of side plate 26. Cartridge frame body 14 includes a cartridge insertion groove 52. The toner cartridge is inserted into cartridge insertion groove 52.
A motor 11 is secured to side plate 26 via a motor base 12. Motor 11 is secured to motor base 12. Motor base 12 is secured to side plate 26 with four screws 13.
In consideration of rotation directions of the plurality of rollers, motor 11 is secured to have a rotation shaft parallel to the horizontal direction. A recess portion 50 is formed in horizontal plate 28 to avoid interference with motor 11. Recess portion 50 is a concave portion extending downward. A portion of motor 11 is arranged in recess portion 50.
Japanese Patent Laying-Open No. 2001-224145 discloses a securing structure of a motor in a portable printer. This publication discloses that a protrusion of a motor cover is inserted into a screw hole for attaching a motor to fit a pair of snap plates arranged on a tip of the motor cover to a pair of groove plates of a motor housing portion to secure the motor to a reclosable cover.
A laser beam printer apparatus has been made smaller in recent years, and a motor, a plurality of rollers and the like are arranged in positions adjacent to each other.
Referring to FIG. 12, recess portion 50 is formed in horizontal plate 28 to ensure an arrangement region of the motor and avoid interference between horizontal plate 28 and motor 11. Screws 13 securing motor base 12 to side plate 26 are arranged on four corners of motor base 12.
During manufacturing of the laser beam printer apparatus, screw 13 arranged on an upper side can be readily fastened with a tool. Screw 13 arranged on a lower side, however, is difficult to fasten because the screw is arranged in recess portion 50, and therefore workability is decreased.
During maintenance such as inspection or repair, screw 13 arranged on the lower side is difficult to remove because the screw is hidden in recess portion 50. When a failure of motor 11 occurs and motor 11 is to be replaced, for example, motor 11 must be removed by using a special tool or after separating side plate 26 from horizontal plate 28.